Every time i try to download my purchased app this alway show up,i try everything from youtube but it’s not working at all.

You need to tap Continue and sign in to view your billing information.

To verify / view your payment information: Sign in to your Apple ID account page and edit / update your Apple ID details -> https://appleid.apple.com                                                     

On the Sidebar click Payment methods -> then tap Payments Methods and tap Manage payment method.